The present invention relates in general to a device for measuring physical properties or concentration of particles and, in particular, to a sensor which includes optical indicating means arranged in an indicator layer in which the particles are dispersed, a light source and an optical indicator including at least one photoelectric receiver for measuring light emitted by the optical indicating means.
Arrangements for optical measurement of physical parameters or concentration of particles have been hitherto assembled of structural modules including an optical device for measuring light, and an indicator space containing the optical indicating means. The overall device has proven to be robust or bulky for many fields of application.
In order to use this measuring principle in new fields of application, the prior art arrangement is to be reduced in size and simultaneously the output signals should be improved.